Nearly 100,000 families could lose their health coverage under Covered California unless they meet a deadline at the end of Tuesday.

Earlier this year, several legal immigrants signed up for health coverage at local events. They were required to prove their legal status to Covered California within a matter of months, but close to 100,000 of them have not done so.

Wednesday at midnight is the absolute deadline.

"This is serious business. This isn't just a threat," said Dana Howard, a spokesman for Covered California.

Howard says if legal status is not verified by Covered California by the deadline, then those immigrant families face a loss of health coverage.

"If you do end up having your coverage terminated, then you're going to have to go through a reinstatement process, which will not be fun," Howard said.

As proof of status, Covered California accepts a U.S. passport, naturalization certificate, U.S. birth certificate and driver's license, or a state-issued identification card, according to its website.

Those already under Covered California will be receiving a renewal notice in October. Those without health insurance can participate in open enrollment from Nov. 15 to Feb. 15, 2014.